The following is a discussion of Halachic topics related to the Parsha of the week.
For final rulings, consult your Rav.

Perhaps father will feel me and I shall appear to him as a mocker (27:12)

IS IT EVER PERMITTED TO LIE?

Yaakov Avinu was the amud ha-emes, the Pillar of Truth. Indeed,
according to the Talmud (1), the greatest fear that Yaakov Avinu
had was that he might encounter life situations where he would
be forced to lie. When Rivkah commanded Yaakov to falsely
present himself to his blind father as Eisav, he protested, for
our Sages (2) compare lying to idol worship. It was only when
Rivkah told him that it was the will of Heaven that he be the
one to receive the blessings from his father Yitzchak, that
Yaakov relented and allowed his mother to disguise him to appear
as Eisav.

What is the definition of lying? R' Yonah (3) lists nine
different categories of liars. In order of severity, they are:

People who cheat in business, causing others financial loss;

People who exploit others after gaining their trust through deception;

People whose lies cause others to lose out on some gain or benefit that was coming to them;

People who fabricate stories merely for the sake of lying;

People who hold out the promise of giving another person material goods while never intending to follow up on their promise;

People who intend to keep a promise but do not honor their commitment;

People who claim that they did a favor or a good deed for another when in fact they have not;

People who praise themselves for virtues that they do not possess;

People who change minor details when retelling an episode.

A careful analysis of these nine categories shows that all of
the lies are told either for the purpose of cheating another
person, or for self-glorification, etc. R' Yonah, however, does
not list those who lie for a "good" purpose or for a "good"
reason. Thus, we may ask, is it ever permitted to lie?

Throughout Talmudic literature, we find stories about our Sages
veering from the truth for "good" reasons (4). Obviously,
however, only the poskim can draw practical conclusions from
such cases, since these very episodes can be understood on
various levels. Moreover, not everything quoted in the Talmud is
applied in practical Halachah, as we often rule differently from
an opinion stated in the Talmud. The following, however, are
some real-life situations with which the poskim deal:

If one is asked information about a matter that is supposed to
remain secret, he may answer, "I don't know" (5). Similarly,
although one is not allowed to lie in order to avoid telling bad
news (6), it is permitted to say, "I don't know" (7).

During an appeal for funds, one is not allowed to announce a
donation in an amount greater than he is planning to give, even
if the aim is to spur others to commit themselves to larger
donations (8).

A wealthy man is permitted to lie about his wealth if he fears
"the evil eye" (ayin ha-ra) or if he does not want to arouse
jealousy (9).

When collecting funds for a poor Torah scholar, one may say that
he is collecting for hachnasas kallah, marrying off a bride, if
he thinks that people will be more receptive to that cause (10).
It is also permitted to raise funds for hachnasas kallah even
when the collection is primarily for the benefit of the
groom (11).

It is prohibited to lie for the sake of financial gain, even
when no stealing is involved (12).

If one fears that a package will be mishandled, it is permitted
to write "glass" on it, even though it does not contain any
glass (13).

If one sees that his wife will be late for Shabbos, he is
permitted to tell her that the hour is later than it really is.
This is permitted only when it is clear that she is
procrastinating. If, however, she is rushing and harried and
telling her that the hour is later than it really is will only
pressure her further, it is forbidden to do so (14).

If, by refusing to receive a visitor, the visitor's feelings
will be hurt, one is permitted to leave instructions saying that
he is not home (15). One should not, however, instruct a minor to
lie about his parents' whereabouts, since that teaches the child
to lie.

FOOTNOTES

1 Makkos 24a.

2 Sanhedrin 92a.

3 Sha'arei Teshuvah 3:178-186.

4 See, for example, Berachos (43b)--episode with R' Papa;
Pesachim (112a)--attributing a statement to a fabricated source
so that it will be readily accepted; Sukkah (34b)--quoting
Shemuel's threat to the haddasim merchants; Yevamos (65b)--
lying for the sake of peace; Bava Metzia (23b)--departing from
the truth for the sake of humility, modesty or discretion; Bava
Metzia (30a)--episode with R' Yishmael. There are many other
such examples.

10 Teshuvos Mishneh Sachir (end of vol. 1) quoting a story with
the Chasam Sofer. Part of the ruling is based on the Midrash
Rabbah (Ki-Sisa) that compares a talmid chacham to a kallah. In
that story the Chasam Sofer allowed a tzedakah fund intended for
hachnasas kallah to support a well-known talmid chacham.

15 Harav S.Z. Auerbach and Harav S.Y. Elyashiv quoted in Titen
Emes L'yaakov, pg. 76. See also Machatzis ha-Shekel O.C. 156
which states that if one has no time to answer a question about
a particular subject, he may say that he is not learning that
subject now and cannot answer the question.